Children who suffer from Hutchinson-Gilford Progeria syndrome age prematurely due to a defective protein in their cells. Scientists at Technische Universität München have now identified another important pathological factor: ...

In pathology, cells and cell nuclei are usually examined using a microscope for bio-marker expressions in tumours. This analysis is used to weigh up the treatment options for patients who have cancer, for example. The certainty ...

Adult stem cells and cancer cells have many things in common, including an ability to migrate through tiny gaps in tissue. Both types of cells also experience a trade-off when it comes to this ability; having a flexible nucleus ...

Incorrectly positioned nuclei are not merely a sign but a possible cause of human congenital myopathies, a string of inherited muscle diseases, Victoria Schulman, graduate student at Weill Cornell Graduate School of Medical ...

The human body has hundreds of different cell types, all with the same basic DNA, and all of which can ultimately be traced back to identical stem cells. Despite this fundamental similarity, a bone cell has little in common ...

Neurobiologists at Heidelberg University have identified calcium in the cell nucleus to be a cellular "switch" responsible for the formation of long-term memory. Using the fruit fly Drosophila melanogaster as a model, the ...

(Medical Xpress)—Researchers at Kanazawa University Graduate School of Medical Science in Japan have determined how APOBEC proteins mediate hypermutations that inhibit viral replication. They also identify the host factor ...

Misshapen cell nuclei are frequently observed in the cells of people with cancer and other diseases, but what causes the abnormality—and why it is associated with certain disorders—has remained unclear.

(Medical Xpress) -- Johns Hopkins researchers say they have discovered one of the most important cellular mechanisms driving the growth and progression of meningioma, the most common form of brain and spinal cord tumor. A ...

(Medical Xpress) -- If you throw a rubber balloon filled with water against a wall, it will spread out and deform on impact, while the same balloon filled with honey, which is more viscous, will deform much less. If the balloon's ...

May 01, 2012

0
0

Cell nucleus

In cell biology, the nucleus (pl. nuclei; from Latin nucleus or nuculeus, or kernel), also sometimes referred to as the "control center", is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these chromosomes are the cell's nuclear genome. The function of the nucleus is to maintain the integrity of these genes and to control the activities of the cell by regulating gene expression--the nucleus is therefore the control center of the cell.

The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and separates its contents from the cellular cytoplasm, and the nuclear lamina, a meshwork within the nucleus that adds mechanical support, much like the cytoskeleton supports the cell as a whole. Because the nuclear membrane is impermeable to most molecules, nuclear pores are required to allow movement of molecules across the envelope. These pores cross both of the membranes, providing a channel that allows free movement of small molecules and ions. The movement of larger molecules such as proteins is carefully controlled, and requires active transport regulated by carrier proteins. Nuclear transport is crucial to cell function, as movement through the pores is required for both gene expression and chromosomal maintenance.

Although the interior of the nucleus does not contain any membrane-bound subcompartments, its contents are not uniform, and a number of subnuclear bodies exist, made up of unique proteins, RNA molecules, and particular parts of the chromosomes. The best known of these is the nucleolus, which is mainly involved in the assembly of ribosomes. After being produced in the nucleolus, ribosomes are exported to the cytoplasm where they translate mRNA.